Schistosomal Colonic Polyposis Mimicking Colorectal Malignancy: A Case Report

Abstract

Colonic schistosomiasis is a parasitic disease that can cause various colorectal lesions, including inflammatory granulomas, ulcers, pseudopolyps, and polyps. These lesions may mimic colorectal neoplasia and make the diagnosis challenging. We report the case of a 17-year-old female with no significant medical or surgical history who presented with a dysentery-like syndrome characterised by bloody stools and severe hypogastric pain. She also reported anorexia, asthenia, and unquantified weight loss. Physical examination revealed a poor general condition. Laboratory investigations showed microcytic hypochromic anaemia. Abdominal CT revealed sigmoid wall thickening associated with lymphadenopathy. Colonoscopy demonstrated a large stenosing, ulcerated, polypoid lesion of the sigmoid colon, highly suggestive of a colonic tumour. Surgical management consisted of sigmoidectomy with regional lymph node dissection. Histopathological examination revealed an inflammatory infiltrate composed of eosinophils, neutrophils, and lymphoplasmocytes surrounding Schistosoma eggs, without atypia, confirming the diagnosis of schistosomal bilharzioma. The patient received praziquantel as a single dose of 40 mg/kg, in addition to a blood transfusion, with a favourable clinical course. Colonic schistosomiasis may present as a stenosing polypoid lesion mimicking colorectal cancer. In endemic areas, schistosomiasis should be considered in the differential diagnosis of colorectal polyps, particularly in patients presenting with dysentery, rectal bleeding, anaemia, or deterioration in general condition. Colonoscopy with histological examination remains essential for establishing the diagnosis.